1. Field of the Invention
This invention relates generally to medical diagnostic instruments and more specifically to a hand-held opto-diagnostic instrument having an adaptor for connecting the medical instrument to a video camera.
2. Discussion of Related Art
Hand-held medical instruments for use by a physician in the optodiagnosis of patients have been kayown for some time. Such hand-held instruments include the otoscope and ophthalmoscope. The hand-held optodiagnostic medical instruments often include a plurality of lenses typically arrayed on one or more discs contained within the instrument head housing which can be manipulated by the physician to selectively dispose a lens or combination of lens, disclosed in more detail by U.S. Pat. No. 4,643,546 to Richards, U.S. Pat. No. 4,526,449 to Newman et al., and U.S. Pat. No. 4,998,818 to Kugler et al., which have been assigned to a common assignee together with the present application and are incorporated herein by reference. The physician selects a lens or combination of lenses for the desired optical properties appropriate for the inspection of a specific target area. The physician selects a lens or a combination of lenses to adjust for the target area being viewed, the patient's refractive error, and the physician's refractive error. The diopter of the specific lens or combination of lenses selected is indicated through a window in the housing of the medical instrument, as is known in the past.
It is also known in the art to employ video technology in combination with hand-held diagnostic medical instruments through the use of an adapter which is removably secured to the instrument, as disclosed by U.S. Pat. No. 5,239,984 granted Aug. 31, 1993 to Cane et al., which is incorporated herein by reference. The adapter utilizes a beam splitter which provides two optical outputs. One of the optical outputs goes to the medical system eyepiece to enable the physician to obtain a direct view of the target area, such as the retina of the eye. The second optical output goes to a video camera head, typically a solid state imager such as a charged coupled device. This allows for video output of the target area for use in producing hard copy photographs, real-time video display, or telecommunication links to remote video hook-ups.
One difficulty experienced in the use of such instruments is the inability of the physician to view the window in the housing of the medical instrument which indicates the diopter of the lens currently in use while the video adapter is employed. When the physician uses the instrument, the physician must view an object through the instrument and adjust the lens dial to obtain proper focus. While keeping the unit aimed at the same object, the physician views the image on the video monitor, and then adjusts the focus ring just above the video camera head until the image is in focus on the monitor.
It is useful to know the value of the diopter of the lens employed because different users may have different refractive errors. Also, a user may change between wearing eyeglasses or not wearing eyeglasses which would require a refocusing of the instrument. An easier view of the diopter value is thus advantageous because it allows the user to reduce the amount of time and effort needed to efficiently operate the instrument.